fix privilege definition on older engines

init.lua

@@ -1,14 +1,27 @@
 creative = {}
 
-minetest.register_privilege("creative", {
-	description = "Allow player to use creative inventory",
-	give_to_singleplayer = false,
-	give_to_admin = false
-	on_grant = update_sfinv,
-	on_revoke = update_sfinv,
-})
-
 local is_53 = minetest.has_feature("object_step_has_moveresult")
+local is_50 = minetest.has_feature("object_use_texture_alpha")
+
+local privs_description = "Allow player to use creative inventory"
+local privs_definition = {}
+
+if is_50 then 
+	privs_definition = {
+		description = privs_description,
+		give_to_singleplayer = false,
+		give_to_admin = false,
+		on_grant = update_sfinv,
+		on_revoke = update_sfinv
+	}
+else
+	privs_definition = {
+	description = privs_description,
+		give_to_singleplayer = false
+	}
+end
+
+minetest.register_privilege("creative", privs_definition)
 
 local creative_mode_cache = minetest.settings:get_bool("creative_mode")